WorksheetsWeek 8
Total questions: 14
Worksheet time: 7mins
Why would you model a component as a rigid body in Abaqus?
To capture plastic deformation more accurately
To reduce contact nonlinearity
To cut computation by replacing many DOFs with up to 6 at a reference node
To enable temperature-dependent material behavior
In Abaqus, the motion of a rigid body is governed by:
The average of all its nodes
A single rigid body reference node
The heaviest node in the mesh
A selected element centroid
For planar/axisymmetric rigid bodies, the reference node has which DOFs?
1, 2 only
1, 2, 3
1, 2, 6
3, 4, 5
When does the position of the reference node matter most?
Only in linear analyses
When rotations or reaction moments about a specific axis are needed
Only in explicit dynamics
Never—position is irrelevant
Compared to discrete rigid bodies, analytical rigid surfaces are generally:
More geometrically flexible and more expensive
Less smooth and noisier in contact
Smoother/cheaper but with more limited shapes
Identical in cost and shape limits
Which statement about loads/BCs with rigid bodies is correct?
You can apply boundary conditions directly to rigid body slave nodes
You can apply loads to nodes/elements belonging to the rigid body
You cannot apply loads to the reference node
Rigid bodies cannot carry any loads
What outputs do rigid elements provide?
Strain/Stress at Gauss points
Only the motion of nodes; reactions at the reference node
Plastic strain contours
Element energy densities
In a rigid body, a pin node vs a tie node:
Pin: translational only; Tie: translational + rotational
. Pin: rotational only; Tie: translational only
Both: translational + rotational
Both: translational only
Hard contact in Abaqus means:
Constraint enforced when clearance ≤ some tolerance; separation allowed only at negative pressure
Constraint enforced only for compressible materials
Unlimited penetration is allowed with a penalty
Contact pressure can be transmitted whenever clearance is positive
The small-sliding approximation is appropriate when:
A point slides a large distance across multiple elements
Relative sliding is a small fraction of a typical element length
Both surfaces are rigid
There is significant surface wear
Master/Slave rules—pick the correct statement:
Node-based surfaces must be master
Analytical rigid surfaces must be master
Slave surface should be the coarser mesh
Stiffer surface should be slave
The element R3D4 designates:
Rigid, 3D, 4-node quadrilateral surface element
Rigid, 2D, 4-node quadrilateral surface element
Deformable, 3D, 4-node tetrahedral element
Rigid beam, 3D, 4-node element
A common, efficient use of rigid bodies in quasi-static forming is to model:
The blank (sheet)
Tooling like punch/die/drawbead/blank-holder
Elastic pads
Only thermal boundaries
A tie constraint:
Prevents normal contact pressure but allows tangential slip
Enforces identical motion between slave nodes and closest points on the master
Couples a surface to a single control point
Is only valid for rigid-to-rigid contact
